Two formal means of communication available to engineers when passing information onto a general audience include written reports and the oral presentations. Each has its own characteristics and when an engineer gives a technical presentation, he or she should focus on those aspects unique to presentations. Table 1 gives a summary of some of the differences.

Table 1. Differences between reports and presentations.

	Presentations	Reports
Primary Transfer	Voice	Text
Secondary Transfer	Slides, Figures	Figures, Tables, Appendices
Audience	Restricted	Unlimited
Time	Limited	Unlimited
Details and Background	Minimal	Yes
Background Review Possible	No	Yes
Review of Previous Material	No	Yes
Emotional Response	Possible	Unlikely
Interaction with Audience	Yes	No
Corrections Possible	Easy	Difficult
Pace	Structured	Unstructured
Captive Audience	Yes	No
Additional Information	Minimal	Yes

As a technical presentation is meant primarily to inform or to persuade, a plethora of text is not required: the presentation should give a summary of the details and any audience member interested in delving further may ask the speaker further questions, or—even better—read the report. The audience is only exposed to each slide for at most one minute, and consequently, a detailed discussion which requires specific knowledge of previous slides may loose the audience. Certain presenters are capable of using dueling projectors, though this requires significant skill and set-up time. Each additional difference should be considered when preparing a presentation.